Summary The pilot departed Prince George, British Columbia, from Runway19 on a flight to Scoop Lake, British Columbia. The aircraft flew on the runway heading until it was about 2400feet beyond the departure end of the runway, where it abruptly pitched up, climbed steeply, turned left, and rapidly descended into trees about 600feet left of the runway's extended centreline. The aircraft was airborne for less than 47seconds and reached a maximum height of about 270feet above ground level. The aircraft was destroyed, and the pilot, who was the sole occupant, was seriously injured. There was no fire. Ce rapport est galement disponible en franais. Other Factual Information General The flight of the Cessna 185B (serial number 185-0601, registration C-FPKJ) originated at Kelowna, British Columbia, where the aircraft was loaded with supplies to be transported to a hunting/fishing camp at Scoop Lake in northern British Columbia. The leg of the flight from Kelowna to Prince George was uneventful, and the aircraft landed at Prince George at 1626 Pacific daylight time,1 where it took on about 115litres of avgas to fill both wing tanks. The aircraft then backtracked to the displaced threshold of Runway19 and was cleared for take-off with a right turn out. Communications between the pilot and air traffic control personnel were normal before take-off, at 1654, for the final leg of the flight to Scoop Lake. There were no communications with the pilot after commencement of the take-off roll. Airport Prince George is a certified airport, equipped with an air traffic control tower. The airport elevation is 2267feet above sea level (asl). Runway19 was the active runway at Prince George at the time of the accident. The asphalt-surfaced runway is 3770feet long and 75feet wide, with a displaced threshold of 370feet. The take-off distance available is 3770feet. Photo1.Departure path from Prince George Airport Weather The observed Prince George weather at 1700, about six minutes after the accident was in part: wind 190T at 11knots, gusting to 18knots; temperature 24.2C; altimeter setting 29.93; and visibility 45statute miles. The wind immediately before take-off was 180M at 10to 15knots. The wind 54minutes before the accident was recorded as gusting to 22knots. Density altitude at the time of the accident was about 3860feetasl. Pilot The pilot was correctly licensed for the type of flight being conducted and had a valid medical. He had accumulated 9150flight hours as of his last medical examination; approximately 5000hours were flown in Cessna185 model aircraft, 2500hours of which were flown in the accident aircraft. The pilot had not flown during the week before the accident flight and was sufficiently rested. Aircraft The aircraft was manufactured in 1963and equipped with a 260HP Teledyne Continental Motors Inc. (TCM) modelIO-470-F engine and a McCauley Propeller Systems D2A34C49-B propeller. The aircraft was modified in 1988by supplementary type certificate (STC)SA525NW, which involved replacement of the original engine with a TCMIO-520-D22B engine, serial number812987, and replacement of the original propeller with a McCauley D2A34C58-O, serial number881880. The replacement engine was overhauled 02March2006, and the propeller was overhauled 16March2006. Both were installed during an annual inspection of the aircraft conducted 12April2006, about 42flight hours before the accident. No maintenance actions were recorded in the aircraft's technical log books following the inspection. Three journey log entries recorded a satisfactory test flight and two adjustments to fuel flow immediately following the inspection. A flight manual supplement was not supplied with STCSA525NW to indicate changes to C-FPKJ's performance following the engine and propeller replacement. Therefore, the modified aircraft would have to be operated within the published performance limitations of an unmodified Cessna185B. Performance Performance information taken from the Cessna 185B owner's manual indicates that, with the aircraft at its allowable gross weight of 3200pounds, the take-off from Prince George would have required a minimum of 840feet of ground run and the maximum rate of climb would have been about 800feet per minute. For a normal take-off, the manual instructs the pilot to use full throttle, maximum rpm, and climb at 95mph until all obstacles are cleared before increasing the airspeed to 110-120mph, reducing the throttle and rpm, and retracting the flaps. Transport Canada's Flight Training Manual notes that retraction of flaps in flight may cause a change in an aircraft's balance. It was the pilot's practice to climb at 105mph with a low rate of climb to keep the engine cool and increase the forward visibility. There was a global positioning system (GPS)on board the aircraft. Data from the GPS were analyzed and indicated the following: the ground run was about 990feet; the aircraft was airborne for 47seconds; the aircraft reached a height of about 270feet above ground level; and the average climb rate was 345feet per minute(fpm). These data were compared to the aircraft's previous take-off from Kelowna and, taking into account the 11-knot headwind and 3860-foot density altitude at Prince George, the take-off profiles were similar. The aircraft reached a maximum speed of about 104mph a few seconds before its steep climb, abrupt turn and rapid descent. It is possible that the steep climb occurred coincident with the retraction of the flaps. Weight and Balance No cargo manifest or aircraft weight and balance information could be located for either leg of the accident flight. All rear seats had been removed, leaving only the pilot's and co-pilot's seats installed at the time of the crash. Cargo weighing about 665pounds was recovered at the accident site. The cargo was distributed from the co-pilot's foot well, aft throughout the cabin to the baggage compartment bulkhead. No cargo restraint system had been used. A substantial number of containers had broken during impact and spilled their contents. This cargo could not be recovered, so its weight was not included in post-crash calculations. Weight and balance calculations based on the weight of recovered cargo and on other known information determined that the aircraft weighed at least 3077pounds at take-off from Prince George. Therefore, the aircraft was not more than about 120pounds below its maximum allowable take-off weight when it departed Prince George. Had all the cargo been recovered and weighed, the aircraft would have been close to its maximum allowable take-off weight. Calculations based on reported cargo distribution within the aircraft indicate that its centre of gravity (CG)was about 0.7inches forward of the aft limit of the certificated envelope. A properly loaded aircraft will tend to stay in the attitude and airspeed at which it is trimmed. Under turbulent conditions, and without the use of cargo restraints, it is possible for the cargo to shift in flight and adversely affect the balance of the aircraft. With an aftCG, the aircraft becomes less stable around the pitch axis and a point can be reached where the aircraft will be uncontrollable. Examinations The propeller, engine, cowls, right wing, and main landing gear separated from the aircraft at impact, and some cargo was ejected. Examination of the airframe did not reveal any pre-impact failures of the aircraft structure or flight control systems. The flaps were found to be fully retracted at impact. The horizontal stabilizer, which can be trimmed by the pilot through a range of 10degrees from full aircraft nose-up to full aircraft nose-down, was found 2.7degrees from the full aircraft nose-down position. Examination of the engine did not reveal any pre-impact defect that would have contributed to a loss of engine power. Some anomalies of various engine accessories were attributed to the post-crash break-up of those components. Examination of the propeller did not reveal any pre-impact defect that would have prevented normal operation. Both propeller blades exhibited slight S-bending, indicative of propeller impact while under power. Witness marks on one blade ferrule made by the actuating pin of the opposite blade indicate that the propeller was at about 15 of pitch at impact, about midrange between the high-pitch stop of 22 and the low-pitch stop of 9.2. The pitch was normal for the climb-out phase of flight. Oil pressure and oil temperature gauges were examined after the accident. Needle slap marks on the gauge faces indicate that the oil temperature was about 140F and the oil pressure was about 60pounds per square inch (psi) at impact, both within normal operating range. Fuel samples taken from the fuelling source at Prince George and from the aircraft's right-wing tank were tested and found to be 100LL avgas, with no contaminates.